A bispecific antibody against human CD3, a T-cell surface antigen, and human guanylate cyclase 2C (GUCY2C; GCC; guanylyl cyclase C; heat-stable enterotoxin receptor; hSTAR), with potential antineoplastic activity. Upon administration, anti-CD3/anti-GUCY2C bispecific antibody PF-07062119 targets and binds to both CD3 on T-cells and GUCY2C expressed on certain tumor cells. This results in the cross-linking of T-cells and tumor cells, and induces a cytotoxic T-lymphocyte (CTL) response against GUCY2C-expressing tumor cells. GUCY2C, a transmembrane receptor expressed on intestinal epithelial cells, is overexpressed on certain tumors of the gastrointestinal (GI) tract.